Equations [1]} that follow and need to be solved self-consistently are
\(|\Delta _{k}| = |{k}| \int d^{2}{q}\; \frac{V(|{q}|)}{8 (2 \pi )^2} |{q}| \sin ^2 (\phi _{q}) \left(1 - \frac{|\Delta _{{k} + {q}}| - |\Delta _{q_F}|}{E_{{k} + {q}}}\right),\) 
